This invention relates to a disk drive which is employed as an external memory means of a computer or the like.
A floppy disk drive (hereinafter referred to merely as "an FDD" when applicable) includes various components which are surrounded by the dotted line in FIG. 1. More specifically, in FIG. 1, reference numeral 1 designates a host computer which uses the FDD as an external memory device; 2, a floppy disk which is inserted in the FDD and can store data; 3, a floppy disk drive motor for turning the floppy disk with a stable speed; 4, a head for reading data off of the floppy disk and for writing data on the latter; 5, a step motor for moving the head 4 radially of the floppy disk 2; 6, a head load actuator for loading the head on and unloading the floppy disk 2, the step motor 5 and the head load actuator 6 forming a head positioning mechanism; and 7, and electronic control section for applying control signals to the head positioning mechanism.
FIG. 2 shows the above-described electronic control section 7 in more detail. In FIG. 2, reference character 7a designates a data read circuit; 7b, a data write circuit, these circuits 7a and 7b being connected directly to the head 4, the circuit 7b being further connected to a write protect detector 9; 7c, a step motor control section for driving the step motor 5; 7d, a head load control section for driving the head load actuator 6; 7e, a door lock control section for driving a door lock actuator 8; and 7f, a position confirming section for confirming, under host computer control, signals from a track "00" signal detector 10 and an index signal detector 11.
The operation of the FDD will be described with reference to FIG. 1.
The floppy disk 2 is turned at a constant speed by the floppy disk drive motor 3. When the host computer 1 writes data in the FDD or reads data out of the latter, the host computer 1 first applies a control signal to the FDD. According to the control signal, the electronic control section 7 moves the head 4 to a position on the floppy disk 2 where data is to be written or read, and then operates the head actuator 6 so that the head 4 is brought into contact with the floppy disk 2. Thereafter, the host computer 1 writes data onto the floppy disk or reads data from the floppy disk magnetically through the head 4 with the aid of the electronic control section 7.
The operation of the conventional electronic control section 7 (surrounded by the dotted line) will be described with reference to FIG. 2. The read circuit 7a shapes the waveform of an electric signal from the head into a desired form irrespective of the track position of the head 4, so as to facilitate data reading by the host computer 1. The data write circuit 7b is an interface circuit which applies write data from the host computer 1 to the head 4. The data write circuit 7b has the function of inhibiting writing when the write protect detector 9 detects a write protect signal.
In the step motor control section 7c, a control signal from the host computer 1 is converted into a phase signal which can directly drive the step motor 5. According to a control signal from the host computer 1 and the state of the FDD, the head load control section 7d applies a signal to the head load actuator 6, to control the vertical movement of the head. Similarly, according to a control signal from the host computer 1 and the state of the FDD, the door control section applies a signal to the door lock actuator, to control the door lock. The position confirming section 7f confirms the relative position of the floppy disk 2, which is a magnetic recording medium, and the head 4 and accordingly informs the host computer.
The blocks 7a through 7f are connected to one another through logic circuits. When it is required to change the operation mode of the FDD depending upon the use thereof, the operator must disconnect or connect the interval wiring in the electronic control section 7.
Thus, even when the method of operating the conventional FDD is changed only slightly (or the operation mode is changed), several circuits must first be disconnected or connected. This preliminary work is troublesome. The FDD cannot operate the head by itself. Therefore, even a simple test of the FDD must be carried out with the aid of the FDD controller (or the host computer).